The present invention relates to conveyor systems and conveying methods and, in particular, to such systems and methods having a multi-fire mode of operation involving multiple diversion points on a single diverter, and a variable fire mode of operation involving a variable diversion point on a single diverter.
Conveyor sorting systems and methods for sorting items (e.g., packages) are common in the prior art. Conventional sorting is accomplished by providing a reader to read a preprinted code on an item to be sorted that has been placed onto the conveyor system, and thereafter activating an appropriate diverter in the proximity of the reader to cause the item to be diverted from the conveyor to an adjacent station. An exemplary prior art sorting system is described in U.S. Pat. No. 4,249,661 (the ""661 patent). Other examples of high-speed sorting apparatus are disclosed in U.S. patent application Ser. Nos. 08/797,025 and 08/752,587, which applications are hereby incorporated by reference.
It is often desirable to sort items traveling on a conveyor into different bins, stackers, conveyors or other devices, referred to generically herein as xe2x80x9cstations,xe2x80x9d off to the side of the conveyer, depending on the nature of the item. Presently, this type of sorting is accomplished using a separate diverter for station, such as illustrated in FIG. 3 of the ""661 patent. However, the need for multiple diverters for such sorting increases the complexity and expense of the conveyer system.
It is also often desirable to sort items of various size based on their position relative to the diverter. For example, for relatively long items it is often desirable to divert the item from the conveyor when its center in the long dimension reaches a mid-point of the diameter. Similarly, for relatively short items it is often preferable to activate (xe2x80x9cfirexe2x80x9d) the diverter when a different portion of the package (e.g., its leading edge) reaches the beginning of the diameter.
As described in U.S. Pat. Nos. 3,242,342, 3,515,254 and 3,512,624, it is known to divert packages from a conveyor when the center of the package reaches the mid-point of the diverter. It is also known to take various actions in a conveyor system as a function of the length of a package being conveyed. See U.S. Pat. No. 3,680,692. Unfortunately, it is believed no conveyor systems exist that determine the length of a package and then fire a diverter when a selected position on the package reaches a selected position on the diverter as a function of the length of the package. As such, known conveyor systems are not particularly well adapted to conveying packages of widely varying lengths, with the result that packages are often misdiverted, turned in an undesirable orientation or not diverted at all.
The present invention relates to conveyor systems and methods, and in particular such systems and methods having a multi-fire operation involving multiple diversion points on a single diverter, and a variable fire operation involving a variable diversion point on a single diverter.
A first aspect of the invention is a diverter system for diverting items to one of a plurality of stations on either side of a conveyor. The diverter system is designed for use with a conveyor for transporting items in a first direction. The conveyor includes at least one diverter region in which the diverter system is positionable. The diverter system comprises a diverter for diverting items transported by the conveyor in the first direction to one of a plurality of stations adjacent the diverter that are spaced from one another in the first direction, when positioned in a diverter region of the conveyor, in response to a fire signal. The diverter system also includes a source of destination information identifying one of the plurality of stations to which items transported by the conveyor are to be diverted, and a controller system connected to the diverter and the source for generating, and providing to the diverter, a fire signal for each item transported by the conveyor based on destination information from the source regarding the one of the plurality of stations to which the item is to be diverted.
A second aspect of the invention is a method of diverting an item traveling on a conveyor having a diverter and a plurality of stations adjacent the diverter onto one of the stations. The method comprising the steps of first, determining the item length LI of the item and an item tracking point on the item, then acquiring station destination information for the item identifying a one of the plurality of stations to which the item is to be diverted. Then, one of a distance or time for the item tracking point to align with the one station is determined. Finally, the diverter is fired when the item tracking point aligns with the one station so as to divert the item to the one station.
A third aspect of the invention is a method of diverting an item traveling on a conveyor having a diverter to a station adjacent the conveyor, the station having a central axis and a divert axis. The method comprising the steps of first, determining an item length LI, a leading edge position and a trailing edge position of the item, then comparing item length LI to a threshold length LR, then, if LI greater than LR, setting an item tracking point to be between the leading edge and the trailing edge position, and if LI less than LR, setting the item tracking point adjacent the leading edge, and then calculating one of a time or a distance for the item tracking point to align with one of the station axis and the divert axis, then, if LI greater than LR, firing the diverter when the item tracking point aligns with the central axis, and if LI less than LR, firing the diverter when the item tracking point aligns with the divert axis.